The charge-flipping algorithm in crystallography
نویسندگان
چکیده
منابع مشابه
The charge-flipping algorithm in crystallography.
The charge-flipping algorithm (CFA) is a member of the diverse family of dual-space iterative phasing algorithms. These algorithms use alternating modifications in direct and reciprocal space to find a solution to the phase problem. The current state-of-the-art CFA is reviewed and it is put in the context of related dual-space algorithms with relevance for crystallography. The CFA has found app...
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This paper summarizes the current state of charge flipping, a recently developed algorithm of ab initio structure determination. Its operation is based on the perturbation of large plateaus of low electron density but not directly on atomicity. Such a working principle radically differs from that of classical direct methods and offers complementary applications. The list of successful structure...
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The structures of two crystals have been solved using a new iterative phasing method. The iterative phasing algorithm is developed from the 'charge-flipping' method proposed by Oszlányi & Süto [Acta Cryst. (2004), A60, 134-141]. Positivity and point-atom constraints are incorporated within this extremely simple and effective algorithm by flipping (sign reversal) of less-positive density values ...
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We demonstrate self-trapped laser beams carrying phase singularities in nematic liquid crystals. We experimentally observe the astigmatic transformation of vortex beams into spiraling dipole azimuthons accompanied by power-dependent charge-flipping of the on-axis phase singularity. The latter topological reactions involve triplets of vortex lines and resemble pitchfork bifurcations.
متن کامل3 Ab initio structure solution by charge flipping
In this paper we present an extremely simple structure solution method termed charge flipping. It works ab initio on high resolution x-ray diffraction data in the manner of Fourier recycling. The real space modification simply changes the sign of charge density below a threshold, while in reciprocal space the modification is the F obs map without any weighting. We test the algorithm using synth...
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ژورنال
عنوان ژورنال: Acta Crystallographica Section B Structural Science Crystal Engineering and Materials
سال: 2013
ISSN: 0108-7681,1600-5740
DOI: 10.1107/s0108768112051361